Under Community Review

Tridion Sites has two types of workflow support embargo (default one) and collaboration
See documentation: https://docs.rws.com/986894/417453/tridion-sites-9-6-main-documentation/workflow-as-embargo-or-workflow-as-collaboration 
Collaboration is not something that allows working simultaneously for multiple users on the same item however it allows to see changes in-progress

Could you please share more use cases for this collaborative editing?

Maybe you have some business cases to share?

What are the main reasons multiple people work on the same item?

- Too much content?

- Content of different types, like marketing and legal content?

- Any other reasons?

Thank you

Does Tridion allow for branching to allow multiple authors in update the same file?

Branching would allow multiple authors to work on a page or content file at the same time. Changes would be merged once content was published.